The use of a windshield wiper system that optimizes the view available to the driver in any weather and climate condition is indispensable for any means of transport, from cars to trucks, from aircraft to watercraft and the like.
For larger vehicles it is necessary to resort to a windshield cleaning system that has a plurality of blades, each designed to wipe a delimited surface of said windshield.
This is the case of large watercraft, whose configuration can include up to five wiper blades or more.
For these systems with at least two blades, the market greatly appreciates systems in which each blade is operated by an electric gearmotor or motor.
In these systems, therefore, when the motors/gearmotors are powered, each blade moves independently of the others.
Shortly after activation, such independent motion of the wiper blades becomes uncoordinated and unpleasant and in the long run detrimental to the attention of the vehicle's pilot and accordingly for the entire crew.
Several synchronization devices for systems provided with at least two wipers are currently known.
A first type of these devices uses encoders to determine the position of the blades and then act on the rotation rate of each electric gearmotor/motor with methods of the PWM (Pulse Width Modulation) type.
A second type of these devices has a parking switch to stop the gearmotors in a given position.
The motor/gearmotor of the first blade that reaches the set position, known as parking position, stops and waits for the remaining blades to reach their respective parking positions.
Then, after a certain time interval required for the arrival of all the blades, the wipers restart together from a motionless condition.
The motors/gearmotors can be stopped by simply not supplying power to them or by short-circuiting the power supply terminals of each motor/gearmotor so that the motor acts as a brake.
These known devices are not free from drawbacks.
Encoder devices are inherently very expensive and also require, for the implementation of such methods of the Pulse Width Modulation type, driving circuits that are unavoidably complex and accordingly also relatively onerous from an economical standpoint.
The devices that can be classified under the second type have disadvantages that are linked above all to the waiting time required for all the wipers to reach the parking position.
Due to the many factors (friction, characteristics of the gearmotor and the like) that affect the wiping interval of a wiper, i.e., the time required by the blade to start and return to the same preset position, this interval may change in an uncontrolled manner with respect to the needs of a pilot, causing such unpleasant uncoordinated motion of the wiper blades.
Moreover, while on the one hand stopping the motors/gearmotors by not supplying them with power and without the aid of a braking system allows the wiper to continue its stroke even for a few seconds, fully to the detriment of the intended synchronization effect, on the other hand resorting to the braking action of the motor often leads to a dangerous overheating of the motors/gearmotors and to the unpleasant feeling of a jerky operation of the wipers.